I'm about to helicoil head bolt hole (#5 in the tightening procedure) on a first gen 350. Motor is fully assembled except for intake and head on the damaged side. The head bolt has more threads than 1 insert. Do I need to match or exceed the number of threads with multiple inserts? I was going to use red locktite on the insert(s) and let sit for 24 hrs. I've read the 'helicoil' threads on the Engine forum. Is it absolutely necessary to break off the tang on the bottom of the insert? Any other advice you can give me?